The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
A gasoline engine works by drawing into its cylinder a mixture of air and fuel which is compressed, then ignited to burn and thus generate power. Known devices, such as those disclosed in JP 03286173, U.S. Pat. No. 5,273,020 and GB2248087, are comprised of the apparatus as herein described, however, the novel method of their control is the basis of this invention.
In the past the fuel air mixture was provided by a carburetor. Now the fuel system is usually electronically controlled and has one or more injectors which deliver fuel to the manifold and/or cylinder. JP 03286173 is considered the closest prior art and discloses the use of a fuel vapour restriction means to reduce the supply of fuel vapour when the demand for power is high and the air-fuel ratio is determined to be at or above a threshold level—thus attempting to optimize the air-fuel ratio and improve the efficiency of the engine.
A gasoline engine works by drawing into its cylinder a mixture of air and fuel which is compressed, then ignited to burn and thus generate power.
In the past the fuel air mixture was provided by a carburettor. Now the fuel system is usually electronically controlled and has one or more injectors which deliver fuel to the manifold and/or cylinder.
It is essential that at the time of ignition a burnable mixture is present in the cylinder near the igniter. As a result the mixture must be controlled to be within ignitable limits. Consequently the volume of air ingested by the engine must be matched to the fuel volume. This is achieved by a throttle valve which limits the intake of air.
The size of engine fitted to almost all cars is such that full power is rarely used and, in particular, in urban traffic the engine is usually operating at a small fraction of its maximum power outlet. Thus the engine is generally operating with the throttle valve partly closed. Consequently the engine suffers significant pumping losses as the air is drawn past this obstruction. This loss is the reason that Otto engines are less economic of fuel than Diesel engines in urban traffic. If this loss could be eliminated Otto engines economy would rise to be close to that of a diesel engine of similar power.
In the past there have been attempts to reduce this loss by supplying the gasoline in vapour form rather than as a liquid. The increased volume of flow then allowed the throttle to be opened wider thus reducing the pumping loss and improving economy. However, supplying the fuel as vapour also limits the maximum amount that can be drawn into the cylinder and hence the maximum power. The economy achieved by fitting a vapouriser to an engine of any given size turns out to be approximately the same as that achieved by fitting a smaller conventionally fuelled engine which has the same maximum power. Consequently vapourisers have been abandoned as economy devices.